So implausible as to elicit disbelief; unbelievable.adjective
Astonishing, extraordinary, or extreme.
Not credible; that cannot be credited; surpassing the possibility of belief.
Surpassing belief as to what is possible; hard to believe; unimaginable; inconceivable.adjective
Not credible; surpassing belief; too extraordinary and improbable to admit of belief; unlikely; marvelous; fabulous.adjective
beyond belief or understanding